J. Bacteriol., Aug 1996, 4870-4876, Vol 178, No. 16
Copyright © 1996, American Society for Microbiology

Replication of a plasmid lacking the normal site for initiation of one strand

EC Becker, H Zhou and RJ Meyer
Department of Microbiology, University of Texas at Austin, USA.

The origin of replication of the plasmid R1162 contains an initiation site for the synthesis of each DNA strand. When one of these sites (oriL) is deleted, synthesis on the corresponding strand is no longer initiated efficiently in vitro by the R1162-encoded replication proteins, and the plasmid is no longer stably maintained in the cell. However, in vivo the two strands of the plasmid duplex molecule are active at a similar level as templates for DNA synthesis, and newly synthesized copies of each strand are incorporated into daughter molecules at a similar rate. No secondary, strong initiation sites on the delta oriL strand were detected in the region of the origin. The delta oriL plasmid induces the SOS response, and this is important for plasmid maintenance even in a recombination-proficient strain. Our results indicate that an SOS-induced host system can maintain an R1162 derivative lacking one of its initiation sites.

This article has been cited by other articles:

• Parker, C., Meyer, R. (2005). Mechanisms of Strand Replacement Synthesis for Plasmid DNA Transferred by Conjugation. J. Bacteriol. 187: 3400-3406 [Abstract] [Full Text]  
• Henderson, D., Meyer, R. (1999). The MobA-Linked Primase Is the Only Replication Protein of R1162 Required for Conjugal Mobilization. J. Bacteriol. 181: 2973-2978 [Abstract] [Full Text]